1. Field of the Invention
The present invention relates to a substrates laminating apparatus and a method, which stick upper and lower substrates disposed to face each other by use of an adhesive.
2. Description of the Related Art
In manufacturing of a liquid crystal panel, laminating of two glass substrates is carried out in a vacuum state through a sealing material which is an adhesive.
Now, a conventionally known laminating process and an apparatus used for the process will be described.
FIGS. 1 to 4 are conceptual diagrams showing the conventional laminating process. First, as shown in FIG. 1, an upper glass substrate 3 and a lower glass substrate 4 are respectively fed to an upper retention head 1 and a lower retention head 2. The upper glass substrate 3 and the lower glass substrate 4 are retained.
The upper retention head 1 is constituted to be movable in X-Y-xcex8 directions and upper and lower directions. The upper retention head 1 and the lower retention head 2 are disposed entirely in a vacuum chamber including a drive unit thereof. Atmospheric pressure is set at this time.
Thus, when the upper glass substrate 3 and the lower glass substrate 4 are respectively fed to the upper retention head 1 and the lower retention head 2, the vacuum chamber is evacuated.
Then, as shown in FIG. 2, supply pressure to an air cylinder for suspending and supporting the upper retention head 1 is stopped to lower the upper retention head 1 by its dead weight, and the upper glass substrate 3 is abutted on the lower glass substrate 4 through a sealing material 5. Subsequently, compressed air of preset pressure is supplied to the air cylinder, a lifting force is applied to the upper retention head 1, and the upper glass substrate 3 and the lower glass substrate 4 are pressed to each other by a predetermined pressing force based on a difference between the dead weight of the upper retention head 1 and the lifting force of the air cylinder. Prior to the lowering of the upper retention head 1, a state of deviation in relative positions between the glass substrates is detected by use of a camera or the like. When necessary, the upper retention head 1 is moved in X-Y directions or a xcex8 direction to correct the state of deviation.
On an upper surface of the lower glass substrate 4, as shown in FIG. 4, a sealing material 5 is applied beforehand in a closed loop shape along a substrate edge. This sealing material 5 serves as a weir to prevent a flowing-out of a liquid crystal 6 dripped onto the lower glass substrate 4. Thus, by the pressing of the upper glass substrate 3, the two glass substrates 3, 4 are laminated together through the sealing material 5, and the liquid crystal is sealed between the glass substrates.
Then, the vacuum state in the vacuum chamber is released to return to the atmospheric state, the retentions by the upper retention head 1 and the lower retention head 2 are released, and the upper retention head 1 is raised as shown in FIG. 3. The glass substrates which have been laminated together are discharged out of the laminating apparatus.
With enlargement of liquid crystal panels in recent years, the glass substrates 3, 4 treated by the laminating apparatus also tend to be enlarged. Therefore, the upper and lower retention heads 1, 2 for holding the glass substrates 3, 4 must accordingly be enlarged, and the following problem is likely to occur.
That is, the enlarged retention heads 1, 2 are also increased in weight. In the laminating of the glass substrates 3, 4, if the heavy upper retention head 1 is lowered, a pressing force more than necessary is applied on the glass substrates 3, 4 by the dead weight of the upper retention head 1 when the upper glass substrate 3 and the lower glass substrate 4 are abutted on each other, thus an impact fore thereby causes damages to the glass substrates 3, 4.
Objects of the present invention are to provide an apparatus and a method for laminating substrates, which can improve yield by reducing an impact force applied to an upper substrate and a lower substrate to prevent damages of the substrates when substrates are laminated.
According to the present invention, there is provided a substrate laminating apparatus including: an upper retention head for holding an upper substrate; a lower retention head which holds a lower substrate and is disposed while facing the upper retention head, the upper and lower retention heads laminating the upper and lower substrates so as to interpose adhesive therebetween, which are respectively held by the lower and upper retention heads, by allowing the lower and upper retention heads to be close to each other relatively; an elevating apparatus for relatively moving the upper retention head and the lower retention head in upper and lower directions; and a lifting force application apparatus for applying a lifting force to at least one of the upper retention head and the lower retention head at least when the upper substrate held by the upper retention head and the lower substrate held by the lower retention head are abutted each other through the adhesive by the elevating device.